Algae is a primitive form of life, a single-celled or simple multiple-celled organism that is able to conduct the process of photosynthesis. It is generally found in water but can also be found elsewhere, growing on such surfaces as rocks or trees. The various types of algae are 5 classified according to pigment.

Blue-green algae, or Cyanophyta, can grow at very high temperatures and under high-intensity light. This type of algae is the oldest form of life with photosynthetic capabilities. Fossilized remains of 10 blue-green algae more than 3.4 billion years old have been found in parts of Africa.

Green algae, or Chlorophyta, is generally found in fresh water. It reproduces on the surfaces of enclosed bodies of water such as ponds 15 or lakes and has the appearance of a fuzzy green coating on the surface of the water.

Brown algae, or Phaeophyta, grows in shallow, temperate water. This type of algae is the largest in size and is most recognizable 20 as a type of seaweed. Its long stalks can be enmeshed on the ocean floor, or it can float freely on the ocean's surface.

Red algae, or Rhodophyta, is a small, delicate organism found in the deep waters of the subtropics. This type of algae has an essential role 25 in the formation of coral reefs: it secretes lime from the seawater to foster the formation of limestone deposits.

1. What is the author's main purpose?(A) To show what color algae is(B) To differentiate the various classifications of algae(C) To describe where algae is found(D) To clarify the appearance of different types of algae2. Which of the following is NOT true about algae?(A) All types have one cell only.(B) It can be found out of water.(C) It can use photosynthesis.(D) It is not a relatively new form of life.3. The word "pigment" at the end of the first paragraph means(A) size(B) shape(C) composition(D) color4. Algae remnants found in Africa are(A) still flourishing(B) photogenic(C) extremely old(D) red in color5. Green algae is generally found(A) on the ocean floor(B) on top of the water(C) throughout ponds and lakes(D) surrounding enclosed bodies of water6. Brown algae would most likely be found(A) on trees(B) near green algae(C) on rocks(D) in the ocean7. According to the passage, red algae is(A) sturdy(B) huge(C) fragile(D) found in shallow water8. It can be inferred from the passage that limestone deposits serve as the basis of(A) coral reefs(B) red algae(C) subtropical seawater(D) secret passages